Graphical user interfaces are widespread in the field of genome informatics, and are considered key to the success of many application programs. Currently, a developer must choose between creating one from scratch, or working within large-scale, highly integrated systems that may impose monolithic designs and involve high start-up costs. The investigators are developing a toolkit for interface design based on the notion of a domain-specific widget set, where widgets are high level objects that are concerned exclusively with graphical display, hiding the details of placement, drawing, motion, interaction, etc. from the application programmer to the extent possible. Using the Tcl/Tk graphical user interface design system, the investigators have prototyped chromosome, map, and sequence widgets, as well as a number of dialogs and utilities that should promote the development of communicating small applications with a consistent "look and feel." The investigators propose to: improve existing widgets and dialogs, making them significantly more robust and versatile; design new widgets, dialogs, utilities, and database interfaces to support a wider range of applications; reimplement for efficiency and compatibility, creating a compiled and highly tuned widget set for UNIX, Macintosh, and PC platforms, as well as additional software environments including the WWW; create applications in collaboration with biologists, as demonstrations and to drive widget design; and support and archive widgets, dialogs, utilities, and applications in a repository for software sharing.